Linux Basics

• video: https://techworld-with-nana.teachable.com/courses/devops-bootcamp/lectures/32585025

Introduction to Operating Systems

Tasks of an Operating System

• Resource Allocation and Management

  • Process management

    • What's a process? small unit that executes on the computer
    • each process has own isolated space

  • Memory Management:

    • allocating working memory
    • every application needs some data to work
    • RAM is limited on the computer
    • Memory Swapping
      • happens when you're out of RAM
      • OS swaps memory between applications
      • on app becomes inactive, new one gets resources
      • swapping slows down your computer

  • Storage Management

    • aka secondary memory
    • persisting data long-term
    • hard drive

• Manage File System

  • Stored in a structured way
  • Unix systems: tree file system

• Management of IO Devices

• Security

  • managing users and permissions
  • each user has its own space
  • each user has permissions

• Networking

  • eg.: ports and IP address

Operating Systems Components

Kernel: the heart (or brain) of the operating system

The kernel is the software who talks with the hardware.

Standards

POSIX - Portable Operating Systems

Virtualization

with virtualization no separate hardware needed

• hypervisor:

  • example: virtualbox
  • allows you create a virtual machine
  • you can only give resources you actually have
  • hardware resources are shared

• Benefits:

  • learn and experiment
  • don't endanbger your main OS
  • test your app on different OS

Type 1 vs Type 2 Hypervisor

• Type 2:

  • Virtualbox is type 2.
  • Typically used in personal computers
  • Installed on top of an Operating System

• Type 1:

  • Installed direct on hardware
  • aka bare metal hypervisors
  • examples: VMWare ESXi, MicroSoft Hyper-v
  • for servers
  • used by big companies

• Benefits:

  • efficient usage of hardware resources
  • use all the resources of a performant big server
  • users can choose any resource combinations

• Why are companies adopting Virtualization?

  • abstraction of the operating system from the hardware
  • OS is "portable" file that you can move around: Virtual Machine Image

Install Linux on Virtualbox

Basic installation is pretty straightforward, but after installation there are some useful tweaks to do.

• Share clipboard between host and guest machines:
  • Virtualbox menu -> Machine -> Settings -> Advanced -> Shared Clipboard
• Install Virtualbox extension pack: https://www.virtualbox.org/wiki/Downloads